For several centuries now, the writing of South Asian history has been plagued by a tendency to see the past through the lens of religion – especially Hinduism and Islam, which are commonly understood as essentialized, timeless, and locked in binary opposition, if not mutual hostility.

Suggesting a radically different way of theorizing cultural space, however, Sheldon Pollock recently coined the term "Sanskrit

cosmopolis", referring to the enormous geographic sweep of Indic culture that stretched from Afghanistan through Vietnam from the fourth to the 14th century.

For Pollock, what characterized this cosmopolis was not religion, but the ideas elaborated in the entire corpus of Sanskrit texts which, for more than a millennium, circulated above and across the vernacular world of regional tongues.

These texts embraced everything from rules of grammar to styles of kingship, architecture, proper comportment, the goals of life, the regulation of society, and the acquisition of power and wealth. Fundamentally, the Sanskrit cosmopolis was all about defining and preserving moral and social order, but without privileging any particular religious or ethnic community.

Crucially, it expanded over much of Asia not by force of arms, but by emulation, and without any governing center or fortified frontiers. In those respects it compares with the Hellenized world that embraced the Mediterranean basin and the Middle East after Alexander the Great.

For India, at least, historically, what Pollock theorized was only one instance of such a transregional formation. For the Sanskrit cosmopolis anticipated by some 500 years the advent of a similar phenomenon, a "Persian cosmopolis", which spanned great swaths of West, Central, and South Asia from about the ninth to the 19th century.

These two models of cosmopolitan culture exhibited striking parallels. Both expanded and flourished well beyond the land of their origin, giving each a transregional - indeed, "placeless" - quality. Both were grounded in a prestige language and literature that conferred elite status on their users. They both articulated worldly power - specifically, universal dominion. And while both cosmopolises elaborated, discussed, and critiqued religious traditions, neither was grounded in any specific religion, but rather transcended the claims of any and all religions.

But what exactly was the "Persian cosmopolis"? After the conquest of the Iranian plateau in the seventh century, Iranians' refusal to remain under Arab rule and Arab culture resulted in attempts to recover a rich but submerged pre-Islamic Persian civilization, a movement whose linguistic dimension saw the emergence of New Persian.

This appeared first as a spoken lingua franca across the Iranian plateau. A written form derived from a modified Arabic script appeared in the mid-tenth century, when Persian writers in Khurasan - ie, northeastern Iran, western Afghanistan, and Central Asia - began appropriating the heritage of both Arab Islam and pre-Islamic Iran.

Initially, at least, court patronage - namely, the court of the Samanid dynasty of kings of Khurasan (819-999) - played an important role in these developments. Based in Bukhara (in southern Uzbekistan), the Samanid court straddled major trade routes connecting the Iranian plateau with India to the south, Turkish Central Asia to the north, and, via the Silk Road, China to the east. Bukhara thus lay in a commercially vibrant zone, which was also multi-lingual.

By the 14th century, however, across a vast swath of territory between Anatolia and East Asia, New Persian had become a prestigious literary language, a principal medium used in state bureaucracies, and a contact tongue used in interregional diplomacy. In China, it served not only as a lingua franca, but as the official foreign language in the 13th and 14th centuries. Marco Polo mainly used Persian in China, and in fact, throughout his travels on the Silk Road.

What explains this remarkable development? One factor was the cosmopolitan environment in which New Persian had been incubated. Khurasan in the Samanid era was diverse not only linguistically, but also religiously, with its communities of Jews, Christians, Manichaeans, Zoroastrians, Buddhists, pagans, and shamanists, together with both Shi'ite and Sunni Muslims.

The new tongue thus served as a common linguistic denominator in a multi-ethnic society. Moreover, since it did not serve as the vehicle for any scripture or liturgy, New Persian posed no ideological threat to Arabic, the language of Iran's seventh century Islamic victors.

Persian poetry also played a part in the diffusion of the Persian cosmopolis, in particular Iran's great epic poem, the Shahnama. Begun in late Samanid times and completed in 1010, Firdausi's epic of some 60,000 rhymed couplets self-consciously canonized Iran's pre-Islamic royal history.

Like the language in which it was composed, the Shahnama posed no threat to Arab or Islamic sentiment; to the contrary, it praised the reigning monarch, Mahmud of Ghazni (997-1030) as combining the virtues of both Iranian and Islamic sovereignty.

It also assimilated both the warrior ethos of Central Asian Turks and the heritage of Greek civilization. In Firdausi's hands, Alexander himself was transformed into a great Iranian king, and his mother an Iranian princess, while pre-Zoroastrian heroes were presented as analogs to Vedic Indian gods. In sum, the Shahnama had accommodated Greek, Turkic, and Indian cultures.

As with Sanskrit texts, which freely circulated across a vast expanse of territory, after the 11th century texts written in New Persian travelled astonishing distances, jumping ethnic and political, as well as natural frontiers. Nor did the production of Persian literature have any single geographical epicenter after the Mongols overran Khurasan in the 13th century.

Peoples in regions like the Caucasus or South Asia might retain everyday use of their local languages while cultivating, and even producing, great works of Persian literature. Both the Tamil and even the Malay "tellings" of the popular text One Thousand Questions claimed Persian origins that can be traced to 16th century South India. Similarly, in the 17th century Persian romance works such as the Haft Paykar by Nizami Ganjavi (d 1209) were translated into Bengali for kings of Burma's [now Myanmar's] Arakan coast.

In this way, vernacularized forms of the Persian cosmopolis travelled into the Burmese and Malay worlds of Southeast Asia. This portability of Persian letters across vast geo-cultural space was another dimension of the Persian cosmopolis that found an exact parallel with its Sanskrit predecessor.

In the political realm, the same environment that had nurtured the literary and bureaucratic use of New Persian - the culturally diverse milieu of ninth and tenth century Khurasan - also shaped a particular conception of a universal ruler, or "sultan".

Conceived as occupying a political space above and beyond all ethnic groups and religious communities, this figure was understood as not just universal, but truly supreme. In ninth and 10th century Khurasan under the Samanids, where memories of pre-Islamic Iran were being revived, sultans were endowed with universalist sovereignty associated with pre-Islamic Persian emperors.

Such a conception accorded with the idea of the Persian cosmopolis, which resisted limits to claims of sovereign territory. The same, for that matter, was true of the Sanskrit cosmopolis. Just as the sultans of Delhi claimed to be the "ruler of the surface of the earth," Indian maharajas grandly portrayed themselves as the "asylum of the whole world".

What is more, as early as the 12th century, the Iranian historian Ibn Balkhi made explicit a de facto separation of religion and state. He wrote that kingship in pre-Islamic Iran had been based on the supreme principle of justice, and that every king of that age had taught his heir-apparent the following maxim:

"There is no kingdom without an army, no army without wealth, no wealth without material prosperity, and no material prosperity without justice."

One notes the totalizing nature of this scheme: economy, morality, and politics are all integrated into a single coherent ideology. Equally notable is the central place the author gave to the idea of justice, and his complete omission of any reference to God or religion. As a ruling ideology, this formula would become a stock theme throughout the Persian-speaking world, repeated with only slight variations by a host of writers of the genre of courtly advice literature.

Notably, a ruling ideology that accommodated cultural diversity and focused on the principle of justice facilitated India's incorporation into the Persian cosmopolis. For one thing, an inclusivist Persian political ideology was well-suited for governing a north Indian society that was itself extraordinarily diverse religiously, linguistically, and socially.

For another, in 1206, just decades before the Mongol holocaust in Central Asia and Iran would make refugees of many thousands of uprooted Turks and Iranians, a Persianized state had been established in the heart of the north Indian plain. This was the Delhi sultanate (1206-1526), which inherited the Persianate governing traditions and ideological legacy that had evolved in Khurasan under Samanid rulers.

The presence of this sultanate thus enabled refugees fleeing Mongol invaders to migrate from Central Asia and Iran to north India, where they were received and patronized by the sultanate's officials. Naturally, these refugees implanted in India the entire spectrum of Persian culture that they had brought with them from Central Asia and Iran.

What is perhaps most remarkable about the Persian cosmopolis, however, is how readily its core ideas diffused into territories lying beyond the borders of Persianized states like the Delhi sultanate. A distinctively Persianate ideology privileging the notion of justice and connecting economy, morality, and politics infiltrated peninsular India even while that region was still governed by Hindu rulers. At some time in the 12th or 13th century the Telugu poet Baddena, writing at the Kakatiya court at Warangal, penned these striking lines:

To acquire wealth: make the people prosper. To make the people prosper: justice is the means. O Kirti Narayana! They say that justice is the treasury of kings.

These lines clearly reveal the influence of the Persianate world, for the concept of justice as a central tenet of rulership was completely absent in Sanskrit political thought. Moreover, as in the Sanskrit cosmopolis, these ideals had been borrowed, not imposed.

Apart from political ideology, other components of the Persian cosmopolis diffused throughout India after the thirteenth century, including architecture, dress, courtly comportment, cuisine, and especially, lexicon. As the geographic reach of Persian letters expanded, so did the production of dictionaries, whose compilers endeavored to make literature produced in different parts of the Persophone world mutually comprehensible. From the 14th century dictionaries began to be produced in India, where such works rendered Persian equivalences for words not only in Indian languages, but also in Turkish, Pashto, Aramaic, Greek, Latin, and Syriac.

Indeed, between the 16th and 19th centuries, of all Persian language dictionaries produced anywhere, most were produced in India. From the 14th century on, Persian had become the most widely used language for governance across the subcontinent, as Indians filled the vast revenue and judicial bureaucracies in the Delhi sultanate and its successor states, and later in the Mughal empire (1526-1858) and its successor states.

As a result, Persian terms infiltrated the vocabulary of nearly all major regional languages of South Asia. Vernaculars like Bengali or Telugu are replete with Persian terms pertaining not only to governance, but to commerce, literacy, cuisine, music, textiles, and technologies of all sorts.

To conclude, while it shared much in common with its Sanskrit counterpart, the Persian cosmopolis, unlike its Indic predecessor, had appropriated earlier prestigious and cosmopolitan cultures - namely, pre-Islamic Iran, Arab Islam, and Hellenism. Therefore, when Islam as a religious system diffused through north India and the Deccan, it did so encapsulated within a larger Persianate vessel.

Crucially, it was precisely the non-religious character of this larger Persian cosmopolis that allowed non-Muslims to readily assimilate so many of its aspects. Yet most modern scholarship appears to have missed this, continuing instead to read South Asian history through the narrow lens of religion, and in particular that of Hindu-Muslim confrontation, thereby perpetuating 19th century tropes of Oriental despotism, 20th century tropes of a "clash of civilizations," or 21st-century Western anxieties over Islamist activism.

Richard Eaton is Professor of History at the University of Arizona. He is the author, among others, of Slavery and South Asian History (Indiana University Press) and Islamic History as Global History (American Historical Association). He is working on one of the volumes of the upcoming History of India published by Penguin Books.